1. Field of the Invention
The present invention relates to a magnetic disk cartridge in which a magnetic disk medium is rotated within a casing to perform magnetic recording and reproduction, and more particularly to a magnetic disk cartridge with dust-removing liners provided on the inner surface of a casing.
2. Description of the Related Art
In conventional magnetic disk cartridges, a magnetic disk medium is constructed of a discoid substrate, which is formed from a flexible polyester sheet, etc. This magnetic disk medium has magnetic layers deposited on both sides of the substrate, and is rotatably housed in a casing. The casing is formed by bonding upper and lower shells together, and each shell has a head slot through which a magnetic head is positioned over a recording surface of the magnetic disk medium. This kind of magnetic disk cartridge is used primarily as a recording medium for computers, because it is easy to handle and low-cost.
In the above-described magnetic disk cartridge, if tiny particles (dust, etc.) adhere to the magnetic disk medium, they will cause a dropout error. The problem of this dropout error will arise more easily if the recording density of the magnetic disk medium becomes higher. Hence, for example, in most 3½-inch magnetic disk cartridges, etc., liners for removing tiny particles (dust, etc.) from the magnetic disk medium are arranged on the casing inner surfaces (inner surfaces of the upper and lower shells of the casing) that face both sides of the magnetic disk medium.
In conventional magnetic disk cartridges, the above-described liners are generally formed from a material whose surface is napped, and the napped surface makes contact with the magnetic disk medium. By bringing such a surface into contact with the magnetic disk medium being rotated, tiny particles (dust, etc.) are removed from the magnetic disk medium. However, in conventional magnetic disk cartridges with such liners, there are cases where tiny particles (dust, etc.) cannot be removed sufficiently from the magnetic disk medium.
In conventional magnetic disk cartridges, to enhance the effect of contacting the magnetic disk medium, the dust-removing liner is provided with protrusions that protrude toward the magnetic disk medium. The liner with such protrusions is able to enhance the effect of contacting the magnetic disk medium, so the cleaning effect of the liner is enhanced, but there are cases where even such a liner cannot remove tiny particles (dust, etc.) sufficiently from the magnetic disk medium. Note that in the conventional magnetic disk cartridges, the circumferential width of the protrusions provided on the liner has been made constant from the inner circumference of the liner toward the outer circumference because of the manufacture of the horn of an ultrasonic welding device that welds a liner to a cartridge casing.